//$.noConflict(); // you can use $ instead
(function($)
{
    $.fn.blink = function(options)
    {
        var defaults = { delay:1000 };
        var options = $.extend(defaults, options);
       
        return this.each(function()
        {
            var obj = $(this);
            setInterval(function()
            {
                if($(obj).css("visibility") == "visible")
                {
                    $(obj).css('visibility','hidden');
                }
                else
                {
                    $(obj).css('visibility','visible');
                }
            }, options.delay);
        });
    }
}(jQuery))